Semiconductor device

ABSTRACT

A semiconductor device includes a oxide semiconductor layer, a gate electrode arranged above the oxide semiconductor layer, a gate insulation layer between the oxide semiconductor layer and the gate electrode, a first insulation layer arranged above the oxide semiconductor layer and arranged with a first aperture part, wiring including an aluminum layer arranged above the first insulation layer, the wiring being electrically connected to the oxide semiconductor layer via the first aperture part, a barrier layer including aluminum oxide above the first insulation layer, above the wiring and covering a side surface of the wiring, and an organic insulation layer arranged above the barrier layer.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2016-121685 filed on Jun. 20,2016, the entire contents of which are incorporated herein by reference.

FIELD

The present invention is related to a semiconductor device. Inparticular, the present invention is related to a semiconductor devicein which an oxide semiconductor layer is used in a channel.

BACKGROUND

Recently, a driving circuit of a display device, a personal computer orthe like includes a semiconductor device such as a transistor, a diodeor the like as a microscopic switching element. Especially in a displaydevice, a semiconductor device is used as a selective transistor thatsupplies a voltage or a current in accordance with the gray scale ofeach of pixels and also used in a driving circuit that selects a pixelto which the voltage or the current is to be supplied. Thecharacteristics required of a semiconductor device vary in accordancewith the use thereof. For example, a semiconductor device used as aselective transistor is required to have a low off-current or littlevariance from other selective semiconductors. A semiconductor deviceused in a driving circuit is required to have a high on-current.

To be used in a display device as described above, a semiconductordevice including a channel formed of amorphous silicon, low-temperaturepolysilicon or single crystalline silicon has been conventionallydeveloped. The semiconductor device including a channel formed ofamorphous silicon or low-temperature polysilicon is formed in a processof 600° C. or lower, and therefore can be formed by use of a glasssubstrate. Especially, a semiconductor device including a channel formedof amorphous silicon can be formed with a simpler structure and in aprocess of 400° C. or lower, and therefore can be formed, for example,by use of a large glass substrate referred to as an eighth-generationglass substrate (2160×2460 mm). However, such a semiconductor deviceincluding a channel formed of amorphous silicon has a low mobility andis not usable in a driving circuit.

A semiconductor device including a channel formed of low-temperaturepolysilicon or single crystalline silicon has a higher mobility than thesemiconductor device including a channel formed of amorphous silicon,and therefore is usable as a selective transistor and also in a drivingcircuit. However, such a semiconductor device including a channel formedof low-temperature polysilicon or single crystalline silicon has acomplicated structure and needs a complicated process to bemanufactured. In addition, such a semiconductor device needs to beformed in a process of 500° C. or higher, and therefore cannot be formedby use of a large glass substrate as described above. A semiconductordevice including a channel formed of amorphous silicon, low-temperaturepolysilicon or single crystalline silicon has a high off-current. In thecase where such a semiconductor device is used as a selectivetransistor, it is difficult to keep the applied voltage for a long time.

For the above-described reasons, a semiconductor device including achannel formed of an oxide semiconductor, instead of amorphous silicon,low-temperature polysilicon or single crystalline silicon, has beenprogressively developed recently (e.g., Japanese Laid-Open PatentPublication No. 2012-227521). It is known that a semiconductor deviceincluding a channel formed of an oxide semiconductor can be formed witha simple structure and in a low-temperature process like a semiconductordevice including a channel formed of amorphous silicon, and has amobility higher than that of a semiconductor device including a channelformed of amorphous silicon. It is also known that such a semiconductordevice including a channel formed of an oxide semiconductor has a verylow off-current.

However, an oxide semiconductor is easily influenced by impurities likemoisture, hydrogen and ammonia. When moisture, hydrogen and ammoniaenter an oxide semiconductor layer used for a channel, there occurs aproblem that the characteristics of the semiconductor device are varied.In order to solve this problem, it has been studied to provide a barrierlayer, having a blocking characteristic against moisture or impurities,above the oxide semiconductor layer. However, a conventional structureof a barrier layer does not sufficiently block moisture or impuritiesfrom the exterior of the semiconductor device or the other layers whichconfigure the semiconductor device, which causes a problem that thereliability of the semiconductor device is decreased.

SUMMARY

A semiconductor device according to one embodiment of the presentinvention includes a oxide semiconductor layer, a gate electrode abovethe oxide semiconductor layer, a gate insulation layer between the oxidesemiconductor layer and the gate electrode, a first insulation layerabove the oxide semiconductor layer and a first aperture part arrangedin the first insulation layer, wiring including an aluminum layer abovethe first insulation layer, the wiring being electrically connected tothe oxide semiconductor layer via the first aperture part, a barrierlayer including aluminum oxide above the first insulation layer, abovethe wiring and covering a side surface of the wiring, and an organicinsulation layer arranged above the barrier layer.

A semiconductor device according to one embodiment of the presentinvention includes a gate electrode, a gate insulation layer between thegate electrode and a oxide semiconductor layer, a first insulation layerabove the oxide semiconductor layer and a first aperture part arrangedin the first insulation layer, wiring including an aluminum layer abovethe first insulation layer, the wiring being electrically connected tothe oxide semiconductor layer via the first aperture part, a barrierlayer including aluminum oxide above the first insulation layer, abovethe wiring and covering a side surface of the wiring, and an organicinsulation layer above the barrier layer.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention;

FIG. 2 is a partial exploded diagram of a cross-sectional view of asemiconductor device related to one embodiment of the present invention;

FIG. 3 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention;

FIG. 4 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention;

FIG. 5 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention;

FIG. 6 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention;

FIG. 7 is a diagram showing a cross-sectional structure of an evaluationsample for evaluating the characteristics of a protective layer of asemiconductor device related to one embodiment of the present invention;

FIG. 8 is a TDS spectrum showing the characteristics of a protectivelayer of a semiconductor device related to one embodiment of the presentinvention;

FIG. 9 is a diagram showing electrical characteristics after anacceleration test of a semiconductor device related to one embodiment ofthe present invention;

FIG. 10 is a diagram showing electrical characteristics of a short Llength semiconductor device related to one embodiment of the presentinvention; and

FIG. 11 is a diagram showing electrical characteristics of a short Llength semiconductor device related to one embodiment of the presentinvention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the present invention will be described withreference to the drawings. The disclosure is merely exemplary, andalternations and modifications easily conceivable by a person ofordinary skill in the art without departing from the gist of the presentinvention are duly encompassed in the scope of the present invention. Inthe drawings, components may be shown schematically regarding the width,thickness, shape and the like, instead of being shown in accordance withthe actual sizes, for the sake of clear illustration. The drawings aremerely exemplary and do not limit the interpretations of the presentinvention in any way. In the specification and the drawings, componentsthat are substantially the same as those shown in a previous drawing(s)bear the identical reference signs thereto, and detailed descriptionsthereof may be omitted. The following embodiments are presented for thepurpose of providing a highly reliable semiconductor device and amanufacturing method of such a semiconductor device.

First Embodiment

With reference to FIG. 1, an overview of a semiconductor device 10 inembodiment 1 according to the present invention will be described. Thesemiconductor device 10 in embodiment 1 is usable in a pixel or adriving circuit of a liquid crystal display device (LCD), a spontaneousemission display device using an organic light-emitting diode (OLED)such as an organic EL element, a quantum dot or the like for a displayunit, or a reflection-type display device such as an electronic paper orthe like.

However, the semiconductor device related to the present invention isnot limited to those used in a display device. For example, thesemiconductor device related to the present invention may also be usedin integrated circuits (IC) such as micro-processing units (MPU). Thesemiconductor device 10 of the first embodiment is a semiconductordevice having a structure in which an oxide semiconductor is used as achannel. Although a transistor is exemplified as a semiconductor devicein the first embodiment, this does not limit the semiconductor devicerelated to the present invention to a transistor.

[Structure of a Semiconductor Device 10]

FIG. 1 is a cross-sectional diagram showing a summary of a semiconductordevice related to a first embodiment of the present invention. As isshown in FIG. 1, the semiconductor device 10 includes a substrate 100,an underlayer 110, a gate electrode 120, a gate insulation layer 130, anoxide semiconductor layer 140, a source electrode and drain electrode150, a first insulation layer 160, a wiring layer 170, a barrier layer180, a second insulation layer 190, a first electrode 200, a thirdinsulation layer 210 and a second electrode 220. The semiconductordevice 10 is a bottom-gate type transistor.

The substrate 100 has flexibility. The underlayer 110 is arranged abovethe substrate 100. The gate electrode 120 is arranged above theunderlayer 110. The gate insulation layer 130 is arranged above the gateelectrode 120 and above the underlayer 110 exposed from the gateelectrode 120. The oxide semiconductor layer 140 is arranged above thegate insulation layer 130. The oxide semiconductor layer 140 is arrangedin a region including a channel region of the semiconductor device 10.The source electrode and drain electrode 150 is arranged above the oxidesemiconductor layer 140 and above the gate insulation layer 130 exposedfrom the oxide semiconductor layer 140.

The source electrode and drain electrode 150 exposes a part of the oxidesemiconductor layer 140 at a pattern end part of the source electrodeand drain electrode 150. The film thickness of the oxide semiconductorlayer 140 exposed from the source electrode and drain electrode 150 isthinner than the film thickness of the oxide semiconductor layer 140whose upper part is covered by the source electrode and drain electrode150. In other words, a part of the oxide semiconductor layer 140 in aregion exposed from the source electrode and drain electrode 150 isetched. That is, the semiconductor device 10 is a channel etched typetransistor.

The first insulation layer 160 is arranged above the source electrodeand drain electrode 150, above the oxide semiconductor layer 140 exposedfrom the source electrode and drain electrode 150, and above the gateinsulation layer 130 exposed from the source electrode and drainelectrode 150. Aperture parts 162, 164 are arranged in the firstinsulation layer 160. The wiring layer 170 is arranged above the firstgate insulation layer 160 and is connected to the source electrode anddrain electrode 150 via the aperture parts 162, 164. That is, the wiringlayer 170 is electrically connected to the oxide semiconductor layer 140via the source electrode and drain electrode 150. Although described indetail herein, the wiring layer 170 includes an aluminum layer. Thewiring layer 170 may also be a single aluminum layer or a stacked layerincluding an aluminum layer.

The barrier layer 180 covers the top of the first insulation layer 160,the top of the wiring layer 170, and a side surface of the wiring layer170. In other words, the barrier layer 180 covers a pattern end part ofthe wiring layer 170. The barrier layer 180 contacts the wiring layer170 above the wiring layer 170 and at the side surface of the wiringlayer 170. Although described in detail herein, the barrier layer 180includes an aluminum oxide layer. The barrier layer 180 may also be asingle aluminum oxide layer or a stacked layer including an aluminumoxide layer. The second insulation layer 190 is arranged above thebarrier layer 180. The second insulation layer 190 is an organicinsulation layer including a resin. The barrier layer 180 separates analuminum layer of the wiring layer 170 and the second insulation layer190, and suppresses the second insulation layer 190 contacting thealuminum layer. An aperture part 192 which reaches a top surface of thewiring layer 170 is arranged in the barrier layer 180 and secondinsulation layer 190.

The first electrode 200 is arranged above the second insulation layer190. The second electrode 220 is arranged at a position opposing thefirst electrode 200 and is electrically connected to the wiring layer170 via the aperture part 192.

The third insulation layer 210 is arranged between the first electrode200 and the second electrode 220 and electrically insulates the firstelectrode 200 and second electrode 220. Although the third insulationlayer 210 is arranged above the second insulation layer 190, the thirdinsulation layer 210 has an aperture. The diameter of the aperture ofthird insulation layer 210 is wider than the diameter of the aperturepart 192. The aperture of third insulation layer 210 is arranged at theperiphery of the aperture part 192. That is, the third insulation layer210 exposes a part of an upper surface of the second insulation layer190.

The first electrode 200, the third insulation layer 210 and secondelectrode 220 are capacitors. The third insulation layer 210 is adielectric of the capacitors. Although a structure is exemplified inFIG. 1 in which the second electrode 200 is connected to the wiringlayer 170, the first electrode 200 may also be connected to the wiringlayer 170. Although a structure is shown in FIG. 1 in which the secondinsulation layer 190 exposed from the third insulation layer 210 iscovered by the second electrode 220, the second insulation layer 190 mayalso be exposed from the second electrode 220.

Transmittance to water, hydrogen or ammonia of the barrier layer 180 islower than transmittance to water, hydrogen or ammonia of the thirdinsulation layer 210. That is, in the case where water, hydrogen orammonia is discharged from the second insulation layer 190, thedischarged water, hydrogen or ammonia is blocked by the barrier layer180 and is discharged to the exterior passing through the thirdinsulation layer 210 via an aperture part of the third insulation layer210. Therefore, water, hydrogen or ammonia discharged from the secondinsulation layer 190 is suppressed from reaching the oxide semiconductorlayer 140.

[Material of Each Component Structuring the Semiconductor Device 10]

It is possible to use a polyimide substrate as the substrate 100. Inaddition to a polyimide substrate, it is possible to use an acrylicsubstrate, siloxane substrate or an insulation substrate including aresin such as a fluororesin substrate. Impurities may also be introducedto the substrate described above in order to improve thermal resistanceof the substrate 100. In particular, in the case where the semiconductordevice 10 is a top-emission type display, it is possible to useimpurities which degrade transparency of the substrate 100 since it isnot necessary for the substrate 100 to be transparent. On the otherhand, in the case where it is not necessary that the substrate 100 haveflexibility, it is possible to use a glass substrate, a silica substrateand an insulation substrate including translucency such as a sapphiresubstrate as the substrate 100. In the case where the semiconductordevice 10 is not a display device but an integrated circuit, it ispossible to use a semiconductor substrate such as a silicon substrate, asilicon carbide substrate or compound semiconductor substrate, aconductive substrate such as a stainless substrate, or a substrate whichdoes not have translucency.

The underlying layer 110 may be formed of a material that increases theadhesiveness between the substrate 100 and the gate electrode 120. Theunderlying layer 110 may be formed of, for example, silicon oxide(SiO_(x)), silicon oxide nitride (SiO_(x)N_(y)), silicon nitride oxide(SiN_(x)O_(y)), silicon nitride (SiN_(x)), aluminum oxide (AIO_(x)),aluminum oxide nitride (AIO_(x)N_(y)), aluminum nitride oxide(AIN_(x)O_(y)), aluminum nitride (AIN_(x)), or the like (x and y eachrepresent an arbitrary positive value). Alternatively, the underlyinglayer 110 may have a structure including a stack of films of any of suchmaterials. In the case where a sufficient adhesiveness is guaranteedbetween the substrate 100 and the gate electrode 120, the underlyinglayer 110 may be omitted. The underlying layer 110 may be formed of amaterial that suppresses diffusion of impurities from the substrate 100into the oxide semiconductor layer 140. The underlying layer 110 may beformed of an inorganic insulating material as listed above, TEOS, or anorganic insulating material.

SiO_(x)N_(y) and AIO_(x)N_(y) are respectively a silicon compound and analuminum compound containing nitrogen (N) at a lower content than oxygen(O). SiN_(x)O_(y) and AIN_(x)O_(y) are respectively a silicon compoundand an aluminum compound containing oxygen at a lower content thannitrogen.

The underlying layer 110 described above as an example may be formed bya PVD (Physical Vapor Deposition) method or a CVD (Chemical VaporDeposition) method. Examples of the usable PVD method includesputtering, vacuum vapor deposition, electron beam vapor deposition,plating, molecular beam epitaxy, and the like. Examples of the usableCVD method include thermal CVD, plasma CVD, catalyst CVD (Cat(catalytic)-CVD or hot-wire CVD), and the like. The “TEOS layer” refersto a CVD layer formed of TEOS (Tetra Ethyl Ortho Silicate).

Examples of the usable organic insulating material include a polyimideresin, an acrylic resin, an epoxy resin, a silicone resin, a fluorineresin, a siloxane resin, and the like. The underlying layer 110 may beformed of a single layer or a stack of films of such materials. Forexample, the underlying layer 110 may include a stack of an inorganicinsulating material and an organic insulating material.

The gate electrode 120 may be formed of a commonly used metal materialor a commonly used conductive semiconductor material. For example, thegate electrode 120 may be formed of aluminum (Al), titanium (Ti),chromium (Cr), cobalt (Co), nickel (Ni), zinc (Zn), molybdenum (Mo),indium (In), tin (Sn), hafnium (Hf), tantalum (Ta), tungsten (W),platinum (Pt), bismuth (Bi), or the like. Alternatively, the gateelectrode 120 may be formed of an alloy of such materials or a nitrideof such materials. Still alternatively, the gate electrode 120 may beformed of a conductive oxide semiconductor such as ITO (indium tinoxide), IGO (indium gallium oxide), IZO (indium zinc oxide), GZO (zincoxide containing gallium as a dopant), or the like. The gate electrode120 may have a structure including a stack of films of any of suchmaterials.

Preferably, the material used for the gate electrode 120 is resistant toa heat treatment step in a manufacturing process of a semiconductordevice including a channel formed of an oxide semiconductor, and has awork function with which the transistor is of an enhancement type thatis turned off when a voltage of 0 V is applied to the gate electrode120.

It is possible to use an inorganic insulation material such as SiN_(x),SiN_(x)O_(y), SiO_(x)N_(y), AIN_(x), AIN_(x)O_(y) and AlO_(x)N_(y) asthe gate insulation layer 130. The gate insulation layer 130 can beformed by the same method as the underlayer 110. It is possible to use astructure in which the insulation layers described above are stacked forthe gate insulation layer 130. The gate insulation layer 130 may be thesame material as or a different material than the underlayer 110. Thegate insulation layer 130 is preferred to include a gas component suchas H₂O or a blocking ability of movable ions such as Na for example.

The oxide semiconductor layer 140 may be formed of a metal oxidematerial having the characteristics of a semiconductor. For example, theoxide semiconductor layer 140 may be formed of an oxide semiconductorcontaining indium (In), gallium (Ga), zinc (Zn) and oxygen (O).Especially, the oxide semiconductor layer 140 may be formed of an oxidesemiconductor having a composition ratio of In:Ga:Zn:O=1:1:1:4. Itshould be noted that the oxide semiconductor used in the presentinvention and containing In, Ga, Zn and O is not limited to having theabove-described composition ratio. An oxide semiconductor having adifferent composition ratio is also usable. For example, in order toimprove the mobility, the ratio of In may be increased. In order toincrease the bandgap and thus decrease the influence of light, the ratioof Ga may be increased.

The oxide semiconductor containing In, Ga, Zn and O may contain anotherelement added thereto. For example, a metal element such as Al, Sn orthe like may be added. Instead of the above-described oxidesemiconductor, zinc oxide (ZnO), nickel oxide (NiO), tin oxide (SnO₂),titanium oxide (TiO₂), vanadium oxide (VO₂), indium oxide (In₂O₃),strontium titanate (SrTiO₃), or the like may be used. The oxidesemiconductor layer 140 may be amorphous or crystalline. Alternatively,the oxide semiconductor layer 140 may have a mixed phase of an amorphousphase and a crystalline phase.

It is possible to use a general metal material or a conductivesemiconductor material the same as the gate electrode 120 as the sourceelectrode and drain electrode 150. For example, it is possible to useAl, Ti, Cr, Co, Ni, Zn, Mo, In, Sn, Hf, Ta, W, Pt or Bi and the like asthe source electrode and drain electrode 150. An alloy of thesematerials may also be used as the source electrode and drain electrode150. A nitride of these materials may also be used as the sourceelectrode and drain electrode 150. A conductive oxide semiconductor suchas ITO, IGO, IZO and GZO and the like may also be used as the sourceelectrode and drain electrode 150. A structure in which these films arestacked may also be used as the source electrode and drain electrode150. The material used as the source electrode and drain electrode 150is preferred to include thermal resistance to a heat treatment processin the manufacturing process of the semiconductor device using an oxidesemiconductor as a channel, and a material which has a low contactresistance with the oxide semiconductor layer 140 is preferred to beused.

It is possible to use an inorganic insulation material such as SiO_(x),SiO_(x)N_(y), AlO_(x), AlO_(x)N_(y) or a TEOS layer and the like as thefirst insulation layer 160. The first insulation layer 160 can be formedusing the same method as the underlayer 110. A structure in which theinsulation layers described above are stacked can be used for the firstinsulation layer 160. It is possible to use a material for the firstinsulation layer 160 which includes a large amount of oxygen compared tothe stoichiometric ratio of a material used as the first insulationlayer 160. The first insulation layer 160 may be the same material as ora different material than the gate insulation layer 130.

It is possible to use an insulation material which includes an aluminumoxide such as AlO_(x), AlO_(x)N_(y) or AIN_(x)O_(y) and the like as thebarrier layer 180. In particular, it is possible to use a layerincluding an aluminum oxide such as AlO_(x), AlO_(x)N_(y) and the likeas the main component as the barrier layer 180. It is possible to formthe barrier layer using a sputtering method. Although described indetail herein, by forming the barrier layer 180 using a sputteringmethod, it is possible to form an oxygen doped region in an aluminumlayer exposed at the pattern end part of the wiring layer 170.Therefore, the aluminum layer of the wiring layer 170 can suppresscontact with the second insulation layer 190.

It is possible to use a polyimide resin, acrylic resin, epoxy resin,silicon resin, fluororesin and siloxane resin and the like as the secondinsulation layer 190. The second insulation layer 190 may be aphotosensitive resin or a non-photosensitive resin.

It is possible to use a general metal material or a conductivesemiconductor material the same as the gate electrode 120 or the sourceelectrode and drain electrode 150 as the first electrode 200 and secondelectrode 220. For example, it is possible to use Al, Ti, Cr, Co, Ni,Zn, Mo, In, Sn, Hf, Ta, W, Pt or Bi and the like as the first electrode200 and second electrode 220. An alloy of these materials may also beused as the first electrode 200 and second electrode 220. A nitride ofthese materials may also be used as the first electrode 200 and secondelectrode 220. A conductive oxide semiconductor such as ITO, IGO, IZOand GZO and the like may also be used as the first electrode 200 andsecond electrode 220. A structure in which these films are stacked mayalso be used as the first electrode 200 and second electrode 220.

An inorganic insulation material such as SiO_(x), SiN_(x), SiN_(x)O_(y)or SiO_(x)N_(y) and the like may be used as the third insulation layer210. It is possible to form the third insulation layer 210 by the samemethod as the underlayer 110. The third insulation layer 210 may have astructure in which the insulation layers described above are stacked.The third insulation layer 210 may be the same material as or adifferent material than the underlayer 110. It is preferred to use amaterial with a high dielectric constant as the third insulation layer210. However, the material used for the third insulation layer 210 is amaterial with a higher transmittance to water, hydrogen or ammonia thanthe barrier layer 180.

[Structure of a Pattern End Part of Wiring Layer 170]

FIG. 2 is a partial exploded diagram of a cross-sectional view of asemiconductor device related to one embodiment of the present invention.FIG. 2 is a diagram in which a pattern end part of the wiring layer 170enclosed by the dotted line in FIG. 1 is exploded. Furthermore, astructure of the wiring layer 170 having a three-layered stackedstructure is exemplified in FIG. 2.

As is shown in FIG. 2, the wiring layer 170 includes a first conductinglayer 172, aluminum layer 174 and second conducting layer 176. Thealuminum layer 174 is arranged between the first conducting layer 172and the second conducting layer 176. An oxygen doped region 264 isarranged in the boundary vicinity between the aluminum layer 174 and thebarrier layer 180. Although not shown in the diagram, an oxygen dopedregion may also be arranged between the first conducting layer 172 andthe barrier layer 180, and between the second conducting layer 176 andthe barrier layer 180.

It is possible to use Ti or MoW for example as the first conductinglayer 172 and second conducting layer 176. In addition to Al, it ispossible to use Al-Si in which Si is doped as an impurity or Al-Ti inwhich Ti is doped as an impurity in Al as the aluminum layer. Apart fromthose described above, it is also possible to use an alloy including Alas the aluminum layer.

[Formation Method of Oxygen Doped Region 264]

The oxygen doped region 264 of the aluminum layer 174 is formed byimplanting oxygen ions into the aluminum layer 174. Implantation ofoxygen ions is performed by an ion doping method, ion injection methodor reactive sputtering method and the like.

In the case where oxygen ions are implanted using a reactive sputteringmethod, it is possible to implant oxygen ions while simultaneouslyforming the barrier layer 180 by forming the barrier layer 180 using areactive sputtering method. Specifically, O₂ or Ar and O₂ are used as aprocess gas when forming the barrier layer 180. By using O₂ as a processgas, O₂ is ionized by a plasma to generate negative oxygen ions, and thegenerated negative ions are accelerated in a substrate direction by aplasma sheath. The accelerated negative oxygen ions are implanted to thealuminum layer 174 exposed at the pattern end part of the wiring layer170. In the case where oxygen ions are implanted using a reactivesputtering method, in addition to oxygen Ar which is used as a processgas is also implanted to the oxygen doped region 264. That is, Ar isalso doped into the oxygen doped region 264 in addition to oxygen.

In the case of implanting oxygen ions using the method described above,it is preferred to implant the oxygen ions at an angle close to an anglewhich intersects an inclined surface of an end part of the aluminumlayer 174 in order to implant the oxygen ions as deep as possible. Thatis, it is sufficient to incline a substrate with respect to a biasdirection to the ions when implanting the oxygen ions described above.

[Problems produced by contact between an aluminum layer and resininsulation layer]

Here, problems which are produced when the aluminum layer 174 of thewiring layer 170 and the second insulation layer 190 which is a resininsulation layer contact are explained. In the case where Al is used aswiring, a structure in which the upper part of Al is covered by aconductive layer such as Ti is common. However, when the upper part ofAl is covered by Ti, Al is exposed from Ti at the pattern end part ofthe wiring. When a resin insulation layer is formed above the wiringlayer described above in a state where Al is exposed from Ti, Al and theresin insulation layer come into contact at the pattern end part of thewiring.

As a result of the inventor's research, it was found that a problem isproduced whereby an impurity component included in a resin insulationlayer reacts with Al when Al contacts with the resin insulation layer asdescribed above which leads to Al corrosion or Al dissolving. The widthof the wiring becomes narrow due to the Al reaction described above andin the worst case, the wiring breaks. In addition, as a result of theinventor's research, a problem was determined that when an impuritycomponent included in a resin insulation layer reacts with Al, thedissolved Al component is dispersed within the resin insulation layerwhich leads to a drop in the level of transparency of the resininsulation layer. Specifically, a problem was determined that in thecase where acrylic is used in the resin insulation layer, when Alcontacts the acrylic, the acrylic changes color to yellow. When thelevel of transparency of a resin insulation layer drops, the displayquality of the display device drops.

In order to suppress the problems described above, in the case where aresin insulation layer is formed above wiring using Al, a structure isdemanded in which Al does not touch with the resin insulation layer. Inthe structure shown in FIG. 2, it is possible to suppress the problemsdescribed above since the barrier layer 180 is arranged between thealuminum layer 174 and the second insulation layer 190. Furthermore, byproviding the aluminum layer 174 with oxygen doped region 264 at theboundary vicinity between the aluminum layer 174 and the barrier layer180, even when coverage of the barrier layer 180 is poor, it is possibleto suppress the aluminum layer 174 from contacting the second insulationlayer 190.

It is possible to suppress the wiring layer 170 from becoming narrow orbreaking by providing the structure described above. As a result, it ispossible to obtain the semiconductor device 10 with high reliability. Inaddition, by providing the structure described above, it is possible tosuppress a drop in the level of transparency of the second insulationlayer 190. As a result, it is possible to obtain a display device withhigh display quality.

Second Embodiment

A summary of a semiconductor device related to one embodiment of thepresent invention is explained using FIG. 3. The same numerals orreference symbols attached with letters of the alphabet are attachedafter the same numerals to the same parts or parts having similarfunctions as in the first embodiment and repeated explanations areomitted.

FIG. 3 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention. Although thesemiconductor device 10A shown in FIG. 3 is similar to the semiconductordevice 10 shown in FIG. 1, the semiconductor device 10A is different tothe semiconductor device 10 in that a part of an upper surface of asecond insulation layer 190A is exposed from a second electrode 220A ina region 222A. In the semiconductor device 10A, a part of the secondinsulation layer 190A is exposed from both a third insulation layer 210Aand the second electrode 220A, thereby, even in the case where water,hydrogen or ammonia is discharged from the second insulation layer 190A,the water, hydrogen or ammonia is easily discharged to the exterior froma region where the second insulation layer 190A described above isexposed. Therefore, a rise in internal pressure of the second insulationlayer 190 due to the discharge of water, hydrogen or ammonia issuppressed. As a result, it is possible to suppress the semiconductordevice 10A from breaking.

Third Embodiment

FIG. 4 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention. Although asemiconductor device 10B shown in FIG. 4 is similar to the semiconductordevice 10 shown in FIG. 1, the semiconductor device 10B is different tothe semiconductor device 10 in that a first electrode 200B is connectedto a wiring layer 170B via an aperture part 192B and a plurality ofaperture parts 202B is arranged in the first electrode 200B. Byproviding a structure in which the first electrode 200B is connected tothe wiring layer 170B, it is possible to form the first electrode 200Bimmediately after forming the aperture part 192B. In this case, since afilm other than the first electrode 200B is not formed on the surface ofthe wiring layer 170B exposed in the aperture part 192B, the surface ofthe wiring layer 170B is not altered, and it is possible to obtain agood contact between the wiring layer 170B and first electrode 200B.

According to the semiconductor device 10B, the aperture part 202B isarranged in the first electrode 200B. Therefore, even in the case wherewater, hydrogen or ammonia is discharged from the second insulationlayer 190B, the water, hydrogen or ammonia is easily discharged to theexterior due to the aperture part 202B from a region where the secondinsulation layer 190B is exposed. Therefore, a rise in internal pressureof the second insulation layer 190 due to the discharge of water,hydrogen or ammonia is suppressed. As a result, it is possible tosuppress the semiconductor device 10B from breaking.

Fourth Embodiment

FIG. 5 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention. Although asemiconductor device 100 shown in FIG. 5 is similar to the semiconductordevice 10 shown in FIG. 1, the semiconductor device 100 is different tothe semiconductor device 10 in that an etching stopper 230C is arrangedabove an oxide semiconductor layer 140C corresponding to a channelregion. That is, the semiconductor device 100 is a channel stopper typetransistor.

By arranging the etching stopper 230C above the oxide semiconductorlayer 140C, it is possible to prevent the oxide semiconductor layer 140Cfrom being exposed to etching by channel etching. Therefore, it ispossible to suppress the oxide semiconductor layer 140C from beingaltered due to channel etching. Furthermore, it is possible to suppresswater, hydrogen or ammonia discharged from the second insulation layer190C from reaching the oxide semiconductor layer 140C in a channelregion. As a result, it is possible to obtain the semiconductor device10C with high reliability.

Fifth Embodiment

FIG. 6 is a cross-sectional diagram showing a summary of a semiconductordevice related to one embodiment of the present invention. Although asemiconductor device 10D shown in FIG. 6 is similar to the semiconductordevice 10 shown in FIG. 1, the semiconductor device 10D is different tothe semiconductor device 10 in that a structure is provided in which anoxide semiconductor layer 140D, a gate insulation layer 130D and a gateelectrode 120D are stacked above an underlayer 110D in this order. Thatis, the semiconductor device 10D is a top-gate type transistor.

As is shown in FIG. 6, the semiconductor device 10D includes a substrate100D, an underlayer 110D, a gate electrode 120D, a gate insulation layer130D, an oxide semiconductor layer 140D, a first insulation layer 160D,a source electrode and drain electrode 150D, a barrier layer 180D, asecond insulation layer 190D, a first electrode 200D, a third insulationlayer 210D and a second electrode 220D. The oxide semiconductor layer140D is arranged above the underlayer 110D. The gate insulation layer130D is arranged above the oxide semiconductor layer 140D. The gateelectrode 120D is arranged above the gate insulation layer 130D. Thesource electrode and drain electrode 150D is connected to the oxidesemiconductor layer 140D via aperture parts 162D, 164D arranged in thegate insulation layer 130D and first insulation layer 160D.

In the semiconductor device 10D, the oxide semiconductor layer 140Ddirectly below the gate electrode 120D functions as a channel. In orderto further improve an ON current, the oxide semiconductor layer 140Dfrom a contact region between the source electrode and drain electrode150D and the oxide semiconductor layer 140D to a region directly belowthe gate electrode 120D may be provided with low resistance.

When an upper part of the oxide semiconductor layer 140D in a channelregion is covered by the gate electrode 120D, it is possible to preventwater, hydrogen or ammonia discharged from the second insulation layer190D from reaching the oxide semiconductor layer 140D in the channelregion. As a result, it is possible to obtain the semiconductor device10D with high reliability.

Although the semiconductor device 10D shown in FIG. 6 is exemplifiedwith a structure in which a top-gate type transistor is applied to thesemiconductor device 10 shown in FIG. 1, a top-gate type transistor mayalso be applied to the semiconductor device 10A shown in FIG. 3 to thesemiconductor device 10C shown in FIG. 5.

[Transmittance of the barrier layer 180 and third insulation layer 210with respect to water, hydrogen and ammonia]

Transmittance of the barrier layer 180 and the third insulation layer210 with respect to water, hydrogen and ammonia is explained using FIG.7 and FIG. 8. FIG. 7 is a diagram showing a cross-sectional structure ofan evaluation sample for evaluating the characteristics of a protectivelayer of a semiconductor device related to one embodiment of the presentinvention. Two types of structure (A) and (B) were used as evaluationsamples. Evaluation sample (A) has a structure in which a SiN_(x) film310 formed by a CVD method and an AlO_(x) film 320 formed by asputtering method are stacked in order above a silicon wafer 300.Evaluation sample (B) has a structure in which only a SiN_(x) film 310formed by a CVD method is formed above a silicon wafer 300. In eithersample, the film thickness of the SiN_(x) film 310 is about 200 nm. Thefilm thickness of the AlO_(x) film 320 in evaluation sample (A) is about20 nm. An analysis was performed by a thermal desorption gas analysismethod (TDS method) using the two types of sample shown in FIG. 7.

A TDS analysis is an evaluation means in which an evaluation sample isplaced above a heating stage arranged within a vacuum chamber and themass of a gas discharged from the evaluation sample by increasing thetemperature of the heating stage is measured using a quadrupole massspectrometer. It is possible to specify the type of gas discharged fromthe evaluation sample from a mass analysis of the gas.

FIG. 8 is a TDS spectrum showing the characteristics of a protectivelayer of a semiconductor device related to one embodiment of the presentinvention. The TDS spectrum in FIG. 8 shows the TDS analysis resultsevaluated with respect to the evaluation sample shown in FIG. 7. In theTDS spectrum shown in FIG. 8, the M/z=2 spectrum is data showingdesorption of hydrogen (H₂), and the M/z=16 spectrum is data showingdesorption of ammonia (NH₃). In each of the TDS spectrums, the solidline spectrums 404, 408 are TDS spectrums of the evaluation sample (A)and the dotted line spectrums 402, 406 are TDS spectrums of theevaluation sample (B) in FIG. 7.

As is shown in FIG. 8, in the dotted line spectrum 402 of the evaluationsample (B), a peak showing desorption of H₂ is confirmed in atemperature range of 300° C. to 600° C. On the other hand, in the solidline spectrum 404 of the evaluation sample (A), a peak showingdesorption of H₂ is not confirmed. That is, the AlO_(x) film 320 blockshydrogen discharged from the SiN_(x) film 310 and suppresses that thehydrogen discharges to the exterior. In other words, transmittance ofthe AlO_(x) film 320 with respect to hydrogen is low compared to theSiN_(x) film 310.

Similarly, in the dotted line spectrum 406 of the evaluation sample (B),a peak showing desorption of NH₃ is confirmed in a temperature range of500° C. to 700° C. On the other hand, in the solid line spectrum 408 ofthe evaluation sample (A), a peak showing desorption of NH₃ is notconfirmed. That is, the AlO_(x) film 320 blocks ammonia discharged fromthe SiN_(x) film 310 and suppresses that the ammonia discharges to theexterior. In other words, transmittance of the AlO_(x) film 320 withrespect to ammonia is low compared to the SiN_(x) film 310.

Even in the case where an insulation material including AlO_(x)N_(y) oran aluminum oxide such as AIN_(x)O_(y) is used instead of the AlO_(x)film 320, or in the case where an inorganic insulation material such asSiO_(x), SiN_(x)O_(y) or SiO_(x)N_(y) and the like is used instead ofthe SiN_(x) film 310, similar results to those described above areobtained.

From the results described above, it was confirmed that transmittancewith respect to water, hydrogen and ammonia is lower in the barrierlayer 180 in which an insulation material including an aluminum oxidesuch as AlO_(x), AlO_(x)N_(y) or AIN_(x) O_(y) is used than the thirdinsulation layer 210 in which an inorganic insulation material such asSiO_(x), SiN_(x), SiN_(x)O_(y) or SiO_(x)N_(y) and the like is used.

[Transistor characteristics in the case where AlO_(x) or SiN_(x) is usedas the barrier layer 180]

The results of comparing the transistor characteristics in the casewhere AlO_(x) or SiN_(x) is used as the barrier layer 180 in thestructure of the semiconductor device 10 is explained using FIG. 9 toFIG. 11.

FIG. 9 is a diagram showing electrical characteristics after anacceleration test of a semiconductor device related to one embodiment ofthe present invention. In FIG. 9, transistor characteristics before anacceleration test of a resistance environment (called PCT [pressurecooker test]) are shown by a dotted line, and transistor characteristicsafter a PCT test are shown by a solid line. A PCT test surveys a changein transistor characteristics before and after the PCT test by holding atransistor within a chamber at a temperature of 120° C. and humidity of90% for 120 hours. Furthermore, a measurement of the transistorcharacteristics shown in FIG. 9 was performed at room temperature and ina dark room.

In the transistor characteristics shown in FIG. 9, the transistorcharacteristics of a [barrier layer: SiN_(x)] show transistorcharacteristics in the case where SiN_(x) was used as the barrier layer180 of the semiconductor device 10. The transistor characteristics of a[barrier layer: AlO_(x)] show transistor characteristics in the casewhere AlO_(x) was used as the barrier layer 180 of the semiconductordevice 10. Transistor characteristics of [barrier layer: none] showstransistor characteristics when the barrier layer 180 of thesemiconductor device 10 was omitted. Although there is no significantchange in transistor characteristics in the evaluation samples [barrierlayer: SiN_(x)] and [barrier layer: AlO_(x)] before and after a PCTtest, the transistor characteristics change significantly before andafter a PCT test in the evaluation sample [barrier layer: none]. Thatis, it was determined that a reliability equivalent to SiN_(x) can beobtained by using AlO_(x) as the barrier layer 180. That is, it wasdetermined that AlO_(x) has an equivalent resistance to water asSiN_(x). In other words, it was determined that transmittance of AlO_(x)to water was similarly as low as the transmittance to water of SiN_(x).

FIG. 10 and FIG. 11 are diagrams showing the electrical characteristicsof a short L length semiconductor device related to one embodiment ofthe present invention. The transistor characteristics shown in FIG. 10are characteristics of a semiconductor device when a channellength/channel width is L/W=6/6 μm. The transistor characteristics shownin FIG. 11 are characteristics of a semiconductor device when L/W=3/15μm. The transistor characteristics shown in FIG. 10 and FIG. 11 aredisplayed as overlapping transistor characteristics of ninesemiconductor devices formed in a substrate. Furthermore, themeasurement of the transistor characteristics shown in FIG. 10 and FIG.11 was performed at room temperature in a dark room.

The same as FIG. 9, in the transistor characteristics shown in FIG. 10and FIG. 11, the transistor characteristics of a [barrier layer:SiN_(x)] show transistor characteristics in the case where SiN_(x) wasused as the barrier layer 180 of the semiconductor device 10. Thetransistor characteristics of a [barrier layer: AlO_(x)] show transistorcharacteristics in the case where AlO_(x) was used as the barrier layer180 of the semiconductor device 10. Although many transistorcharacteristic abnormalities occurred in the evaluation sample [barrierlayer: SiN_(x)] in both FIG. 10 and FIG. 11, no transistorcharacteristics abnormalities occurred in the evaluation sample [barrierlayer: AlO_(x)]. That is, it was determined that by using AlO_(x) in thebarrier layer 180, it is possible to suppress water, hydrogen or ammoniafrom reaching an oxide semiconductor layer in a channel region fromother layers. Furthermore, although SiN_(x) has a lower transmittance towater, since hydrogen or ammonia is discharged from the SiN_(x) itself,it is inappropriate as a barrier layer of an oxide semiconductor.

As described above, by using AlO_(x) as a barrier layer 180 of asemiconductor device 10, it was confirmed that it is possible to obtaina semiconductor device with high durability, and it is possible toobtain a semiconductor device with no transistor characteristicabnormalities even in the case of a short L length semiconductor device.

The present invention is not limited to any of the above-describedembodiments or modifications, and may be appropriately altered withoutdeparting from the gist of the present invention.

What is claimed is:
 1. A semiconductor device comprising: an oxidesemiconductor layer; a gate electrode above the oxide semiconductorlayer; a gate insulation layer between the oxide semiconductor layer andthe gate electrode; a first insulation layer above the oxidesemiconductor layer, the first insulation layer having a first aperturepart; a wiring including an aluminum layer above the first insulationlayer, the wiring being electrically connected to the oxidesemiconductor layer via the first aperture part; a barrier layerincluding aluminum oxide, the barrier layer covering above the firstinsulation layer, above the wiring and side of the wiring; and anorganic insulation layer above the barrier layer.
 2. The semiconductordevice according to claim 1, wherein the barrier layer contacts thewiring above the wiring and side of the wiring.
 3. The semiconductordevice according to claim 2, wherein the aluminum layer includes anoxygen doped region in the barrier layer side of the aluminum layer. 4.The semiconductor device according to claim 3, wherein the wiringfurther includes a first conducting layer and a second conducting layer,and the aluminum layer is arranged between the first conducting layerand the second conducting layer.
 5. The semiconductor device accordingto claim 1, further comprising: a first electrode above the organicinsulation layer; a second electrode opposing the first electrode andelectrically connected to the wiring via a second aperture part arrangedin the organic insulation layer; and a second insulation layerelectrically insulating the first electrode and the second electrode andexposing the second aperture part and an upper surface of the organicinsulation layer.
 6. The semiconductor device according to claim 5,wherein transmittance of the barrier layer to water, hydrogen or ammoniais lower than transmittance of the second insulation layer to water,hydrogen or ammonia.
 7. The semiconductor device according to claim 5,wherein the second electrode covers an upper surface of the organicinsulation layer exposed by the second aperture part.
 8. Thesemiconductor device according to claim 5, wherein a part of an uppersurface of the organic insulation layer is exposed from the secondelectrode and the second insulation layer.
 9. A semiconductor devicecomprising: a gate electrode; an oxide semiconductor layer above thegate electrode; a gate insulation layer between the gate electrode andthe oxide semiconductor layer; a first insulation layer above the gateelectrode, a first aperture part arranged in the first insulation layer:a wiring including an aluminum layer above the first insulation layer,the wiring being electrically connected to the oxide semiconductor layervia the first aperture part; a barrier layer including aluminum oxide,the barrier layer covering above the first insulation layer, above thewiring and a side of the wiring; and an organic insulation layer abovethe barrier layer.
 10. The semiconductor device according to claim 9,wherein the barrier layer contacts the wiring above the wiring and sideof the wiring.
 11. The semiconductor device according to claim 10,wherein the aluminum layer includes an oxygen doped region in thebarrier layer side of the aluminum layer.
 12. The semiconductor deviceaccording to claim 11, wherein the wiring further includes a first metallayer and a second metal layer, and the aluminum layer is arrangedbetween the first metal layer and the second metal layer.
 13. Thesemiconductor device according to claim 9, further comprising: a firstelectrode above the organic insulation layer; a second electrodeopposing the first electrode and electrically connected to the wiringvia a second aperture part arranged in the organic insulation layer; anda second insulation layer electrically insulating the first electrodeand the second electrode and exposing the second aperture part and anupper surface of the organic insulation layer.
 14. The semiconductordevice according to claim 13, wherein transmittance of the barrier layerto water, hydrogen or ammonia is lower than transmittance of the secondinsulation layer to water, hydrogen or ammonia.
 15. The semiconductordevice according to claim 13, wherein the second electrode covers anupper surface of the organic insulation layer exposed by the secondaperture part.
 16. The semiconductor device according to claim 13,wherein a part of an upper surface of the organic insulation layer isexposed from the second electrode and the second insulation layer. 17.The semiconductor device according to claim 5, wherein the barrier layercontacts the wiring above the wiring and side of the wiring.
 18. Thesemiconductor device according to claim 17, wherein the aluminum layerincludes an oxygen doped region in the barrier layer side of thealuminum layer.
 19. The semiconductor device according to claim 18,wherein the wiring further includes a first conducting layer and asecond conducting layer, and the aluminum layer is arranged between thefirst conducting layer and the second conducting layer.
 20. Thesemiconductor device according to claim 19, wherein the second electrodecovers an upper surface of the organic insulation layer exposed by thesecond aperture part.